Laboratory based quantitative scoring system for pre-analytical quality indicators in arterial blood gas analysis

Arterial blood gas (ABG) analysis is vital in emergency care setting for assessing respiratory and metabolic status, but its reliability is highly jeopardized by pre-analytical errors, which constitute up to 70 % of laboratory errors. This study evaluated pre-analytical quality indicators (QIs) of ABG testing by reviewing requisition forms and ABG samples at the emergency laboratory of a tertiary care hospital in Delhi, India.

In this descriptive, questionnaire-based study, 205 ABG requisition forms and their corresponding samples collected over one year were assessed manually using a predefined checklist of pre-analytical quality indicators. Parameters included patient identification, requisition completeness, syringe type, tip sealing, labeling, sample volume, sample integrity, presence of clots, red cell sedimentation, and transport time (<30 min). Descriptive statistics were then applied.

The study results revealed major deficiencies. Documentation gaps included omission of collection time (97.07 % of all samples), ventilator/oxygen status mentioning (98.04 %), gender (9.27 %), age (6.34 %), and hospital unit (32.68 %). All samples were collected in inappropriate syringes; 89.27 % had inadequately sealed tips and 95.61 % lacked labeling. Transport delays (>30 min) occurred in 23.41 %, with clotting (14.15 %) and sedimentation (17.07 %) also noted. Inadequate volume (<0.3 mL) was found in 20 % of the total samples. Scores clustered at 8.5-10.5 (81 %), with mean=9.44 (SD=1.04); low (<8.0, 5 %) and outlier (>11.0, 3 %) scores were uncommon.

Significant pre-analytical errors undermine ABG reliability, especially in documentation, collection, and transport. Standardized requisition forms, staff training, adherence to transport timelines, quality monitoring, and use of appropriate ABG syringes are essential to improve result accuracy and patient safety.